Pop superstar Taylor Swift's decision to walk into electoral politics for the first time has driven a rise in online voter registration, especially among young people, according to the website Vote.org.

The nonprofit site, which assists people to register online, reported over 250,000 new registrations since Swift posted a message on photo-sharing application Instagram on Sunday backing two Democratic candidates in her home state of Tennessee and urging people to register.

By comparison, the site recorded 57,000 new registrations in all of August and 190,000 earlier this month.

More than 60 percent of the registrations since Sunday were among voters between 18 and 29 years old, an increase the site said was likely prompted by Swift's post.

"This is a pretty incredible, off-the-charts event," said Raven Brooks, the chief operating officer for Vote.org.

Vote.org acknowledged it was not possible to measure the direct impact of Swift's move, but Brooks noted the rush in young voters was in line with Swift's youthful fan base.

Swift's tremendous reach - a best-selling album and tour as well as 112 million Instagram followers - underscores the way famous personalities can leverage their online presence.

Swift on Tuesday, without declaring any party interest won four awards, including artist of the year, at the American Music Awards in Los Angeles and again urged fans to vote.

Rihanna, a Grammy winner in an Instagram post urged fans to register to vote on Tuesday – the concluding day in 14 states for citizens to do so.

Tight Tennessee Race Polls show the United States Senate contest between Democrat Phil Bredesen and Republican Marsha Blackburn, a staunch supporter of President Donald Trump, virtually tied in a state Trump won by 16 points in 2016.

Swift, who has shunned politics, told her followers she could not support Blackburn due to the congresswoman's record on women's issues and gay rights.

President Donald Trump on Monday called Swift an uninformed voter. "Let's just say I like Taylor's music about 25 percent less now, OK?" he told reporters.

Former Arkansas Governor Mike Huckabee also chimed in saying her endorsements "won't impact the election unless we allow 13 yr old girls to vote."

Galore celebrities identify as liberals, and Democrat Hillary Clinton enjoyed broad support from actors, musicians and other popular figures in 2016.